A study by a team of researchers at VEIC-administered utility Efficiency Vermont has revealed a potential game changer for thermal energy efficiency service providers. Smart thermostats, also known as programmable communicating thermostats (PCTs), already have solid energy-saving credentials, owing to their ability to learn, and adjust to, owners’ patterns of use. The Nest Learning Thermostat, launched in 2011, has generated a lot of interest among consumers for its sleek appearance and accessible user interface. What piqued the recent interest of the research team, however, was Nest’s web-based PCT service for owners: Provision of time-stamped indoor temperature histories, to track energy use.
When linked with weather data, the team wondered, could Nest-generated data reveal a building’s heat loss patterns and, by extension, thermal shell performance? If so, the implications could be profound for energy efficiency service providers accustomed to relying on energy audits to identify buildings in need of thermal retrofits. If remote PCT data analysis could discern shell performance, it had the potential to make thermal energy efficiency program design and delivery notably more targeted and cost-effective.
Efficiency Vermont launched a small-scale study, collecting and analyzing data from 13 Nest thermostats in a diverse group of Vermont homes and small businesses, paired with such information as location and weather conditions. Results revealed a meaningful correlation between building shell performance and the temperature adjustments made by the thermostats in response to indoor heat loss. The research also identified challenges to be addressed before the full potential of PCT data analysis can be realized, and confirmed the benefit of expanding to a large-scale study.
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